docs: def get_mutations(aln_df):
      """Get a list of residue numbers (in the original sequence's numbering) that are mutated
  
      Args:
          aln_df (DataFrame): Alignment DataFrame
          just_resnums: If only the residue numbers should be returned, instead of a list of tuples of
              (original_residue, resnum, mutated_residue)
  
      Returns:
          list: Residue mutations
  
      """
      mutation_df = aln_df[aln_df['type'] == 'mutation']
      tuples = []
      if not mutation_df.empty:
          subset = mutation_df[['id_a_aa', 'id_a_pos', 'id_b_aa']]
          subset['id_a_pos'] = subset['id_a_pos'].astype(int)
          tuples = [tuple(x) for x in subset.values]
      return tuples